A motorcycle or tricycle vehicle equipped with balloon tires is frequently used to run offroad, i.e., on an undulating field so that the fluid level in the float chamber of the carburetor moves up and down. In order to control the fluid level in the float chamber, there has been adopted means in which the float chamber is formed with an overflow port connected with a pipe for discharging the fuel which has overflowed.
While running off the road, however, the vehicle may run in a deep pond or pool. In this instance, since the motorcycle or tricycle structurally has its engine disposed at a relatively low position, the carburetor is also disposed at an accordingly low level. Consequently, if the aforementioned overflow pipe is in a depending position, its open end may dip into the water. This may invite backflow of water into the float chamber so that water is mixed into the fuel, thereby to cause the engine to be troubled or stopped.
The present invention has been conceived in view of the background thus far described and contemplates to provide an overflow device for a vehicular carburetor, by which the backflow of water is blocked to prevent the engine from being troubled or stopped without adversely affecting the overflow function.